// * whether or not a particular block branches out of the loop
// * the successor blocks of the loop
// * the loop depth
-// * the trip count
// * etc...
//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_ANALYSIS_LOOP_INFO_H
-#define LLVM_ANALYSIS_LOOP_INFO_H
+#ifndef LLVM_ANALYSIS_LOOPINFO_H
+#define LLVM_ANALYSIS_LOOPINFO_H
-#include "llvm/Pass.h"
#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/Support/CFG.h"
-#include "llvm/Support/raw_ostream.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Pass.h"
#include <algorithm>
-#include <map>
namespace llvm {
-template<typename T>
-static void RemoveFromVector(std::vector<T*> &V, T *N) {
- typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
- assert(I != V.end() && "N is not in this list!");
- V.erase(I);
-}
+// FIXME: Replace this brittle forward declaration with the include of the new
+// PassManager.h when doing so doesn't break the PassManagerBuilder.
+template <typename IRUnitT> class AnalysisManager;
+class PreservedAnalyses;
class DominatorTree;
class LoopInfo;
class Loop;
+class MDNode;
class PHINode;
+class raw_ostream;
+template<class N> class DominatorTreeBase;
template<class N, class M> class LoopInfoBase;
template<class N, class M> class LoopBase;
//===----------------------------------------------------------------------===//
-/// LoopBase class - Instances of this class are used to represent loops that
-/// are detected in the flow graph
+/// Instances of this class are used to represent loops that are detected in the
+/// flow graph.
///
template<class BlockT, class LoopT>
class LoopBase {
LoopT *ParentLoop;
- // SubLoops - Loops contained entirely within this one.
+ // Loops contained entirely within this one.
std::vector<LoopT *> SubLoops;
- // Blocks - The list of blocks in this loop. First entry is the header node.
+ // The list of blocks in this loop. First entry is the header node.
std::vector<BlockT*> Blocks;
- // DO NOT IMPLEMENT
- LoopBase(const LoopBase<BlockT, LoopT> &);
- // DO NOT IMPLEMENT
- const LoopBase<BlockT, LoopT>&operator=(const LoopBase<BlockT, LoopT> &);
+ SmallPtrSet<const BlockT*, 8> DenseBlockSet;
+
+ /// Indicator that this loop is no longer a valid loop.
+ bool IsInvalid = false;
+
+ LoopBase(const LoopBase<BlockT, LoopT> &) = delete;
+ const LoopBase<BlockT, LoopT>&
+ operator=(const LoopBase<BlockT, LoopT> &) = delete;
public:
- /// Loop ctor - This creates an empty loop.
- LoopBase() : ParentLoop(0) {}
+ /// This creates an empty loop.
+ LoopBase() : ParentLoop(nullptr) {}
~LoopBase() {
for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
delete SubLoops[i];
}
- /// getLoopDepth - Return the nesting level of this loop. An outer-most
- /// loop has depth 1, for consistency with loop depth values used for basic
- /// blocks, where depth 0 is used for blocks not inside any loops.
+ /// Return the nesting level of this loop. An outer-most loop has depth 1,
+ /// for consistency with loop depth values used for basic blocks, where depth
+ /// 0 is used for blocks not inside any loops.
unsigned getLoopDepth() const {
unsigned D = 1;
for (const LoopT *CurLoop = ParentLoop; CurLoop;
BlockT *getHeader() const { return Blocks.front(); }
LoopT *getParentLoop() const { return ParentLoop; }
- /// contains - Return true if the specified loop is contained within in
- /// this loop.
- ///
+ /// This is a raw interface for bypassing addChildLoop.
+ void setParentLoop(LoopT *L) { ParentLoop = L; }
+
+ /// Return true if the specified loop is contained within in this loop.
bool contains(const LoopT *L) const {
if (L == this) return true;
- if (L == 0) return false;
+ if (!L) return false;
return contains(L->getParentLoop());
}
- /// contains - Return true if the specified basic block is in this loop.
- ///
+ /// Return true if the specified basic block is in this loop.
bool contains(const BlockT *BB) const {
- return std::find(block_begin(), block_end(), BB) != block_end();
+ return DenseBlockSet.count(BB);
}
- /// contains - Return true if the specified instruction is in this loop.
- ///
+ /// Return true if the specified instruction is in this loop.
template<class InstT>
bool contains(const InstT *Inst) const {
return contains(Inst->getParent());
}
- /// iterator/begin/end - Return the loops contained entirely within this loop.
- ///
+ /// Return the loops contained entirely within this loop.
const std::vector<LoopT *> &getSubLoops() const { return SubLoops; }
+ std::vector<LoopT *> &getSubLoopsVector() { return SubLoops; }
typedef typename std::vector<LoopT *>::const_iterator iterator;
+ typedef typename std::vector<LoopT *>::const_reverse_iterator
+ reverse_iterator;
iterator begin() const { return SubLoops.begin(); }
iterator end() const { return SubLoops.end(); }
+ reverse_iterator rbegin() const { return SubLoops.rbegin(); }
+ reverse_iterator rend() const { return SubLoops.rend(); }
bool empty() const { return SubLoops.empty(); }
- /// getBlocks - Get a list of the basic blocks which make up this loop.
- ///
+ /// Get a list of the basic blocks which make up this loop.
const std::vector<BlockT*> &getBlocks() const { return Blocks; }
typedef typename std::vector<BlockT*>::const_iterator block_iterator;
block_iterator block_begin() const { return Blocks.begin(); }
block_iterator block_end() const { return Blocks.end(); }
+ inline iterator_range<block_iterator> blocks() const {
+ return make_range(block_begin(), block_end());
+ }
- /// isLoopExiting - True if terminator in the block can branch to another
- /// block that is outside of the current loop.
- ///
+ /// Get the number of blocks in this loop in constant time.
+ unsigned getNumBlocks() const {
+ return Blocks.size();
+ }
+
+ /// Invalidate the loop, indicating that it is no longer a loop.
+ void invalidate() { IsInvalid = true; }
+
+ /// Return true if this loop is no longer valid.
+ bool isInvalid() { return IsInvalid; }
+
+ /// True if terminator in the block can branch to another block that is
+ /// outside of the current loop.
bool isLoopExiting(const BlockT *BB) const {
- typedef GraphTraits<BlockT*> BlockTraits;
+ typedef GraphTraits<const BlockT*> BlockTraits;
for (typename BlockTraits::ChildIteratorType SI =
- BlockTraits::child_begin(const_cast<BlockT*>(BB)),
- SE = BlockTraits::child_end(const_cast<BlockT*>(BB)); SI != SE; ++SI) {
+ BlockTraits::child_begin(BB),
+ SE = BlockTraits::child_end(BB); SI != SE; ++SI) {
if (!contains(*SI))
return true;
}
return false;
}
- /// getNumBackEdges - Calculate the number of back edges to the loop header
- ///
+ /// Calculate the number of back edges to the loop header.
unsigned getNumBackEdges() const {
unsigned NumBackEdges = 0;
BlockT *H = getHeader();
typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
for (typename InvBlockTraits::ChildIteratorType I =
- InvBlockTraits::child_begin(const_cast<BlockT*>(H)),
- E = InvBlockTraits::child_end(const_cast<BlockT*>(H)); I != E; ++I)
+ InvBlockTraits::child_begin(H),
+ E = InvBlockTraits::child_end(H); I != E; ++I)
if (contains(*I))
++NumBackEdges;
// induction variable canonicalization pass should be used to normalize loops
// for easy analysis. These methods assume canonical loops.
- /// getExitingBlocks - Return all blocks inside the loop that have successors
- /// outside of the loop. These are the blocks _inside of the current loop_
- /// which branch out. The returned list is always unique.
- ///
- void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const {
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
- std::sort(LoopBBs.begin(), LoopBBs.end());
-
- typedef GraphTraits<BlockT*> BlockTraits;
- for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
- for (typename BlockTraits::ChildIteratorType I =
- BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
- I != E; ++I)
- if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) {
- // Not in current loop? It must be an exit block.
- ExitingBlocks.push_back(*BI);
- break;
- }
- }
+ /// Return all blocks inside the loop that have successors outside of the
+ /// loop. These are the blocks _inside of the current loop_ which branch out.
+ /// The returned list is always unique.
+ void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
- /// getExitingBlock - If getExitingBlocks would return exactly one block,
- /// return that block. Otherwise return null.
- BlockT *getExitingBlock() const {
- SmallVector<BlockT*, 8> ExitingBlocks;
- getExitingBlocks(ExitingBlocks);
- if (ExitingBlocks.size() == 1)
- return ExitingBlocks[0];
- return 0;
- }
+ /// If getExitingBlocks would return exactly one block, return that block.
+ /// Otherwise return null.
+ BlockT *getExitingBlock() const;
- /// getExitBlocks - Return all of the successor blocks of this loop. These
- /// are the blocks _outside of the current loop_ which are branched to.
- ///
- void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
- std::sort(LoopBBs.begin(), LoopBBs.end());
-
- typedef GraphTraits<BlockT*> BlockTraits;
- for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
- for (typename BlockTraits::ChildIteratorType I =
- BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
- I != E; ++I)
- if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
- // Not in current loop? It must be an exit block.
- ExitBlocks.push_back(*I);
- }
+ /// Return all of the successor blocks of this loop. These are the blocks
+ /// _outside of the current loop_ which are branched to.
+ void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const;
- /// getExitBlock - If getExitBlocks would return exactly one block,
- /// return that block. Otherwise return null.
- BlockT *getExitBlock() const {
- SmallVector<BlockT*, 8> ExitBlocks;
- getExitBlocks(ExitBlocks);
- if (ExitBlocks.size() == 1)
- return ExitBlocks[0];
- return 0;
- }
+ /// If getExitBlocks would return exactly one block, return that block.
+ /// Otherwise return null.
+ BlockT *getExitBlock() const;
/// Edge type.
- typedef std::pair<BlockT*, BlockT*> Edge;
-
- /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_).
- template <typename EdgeT>
- void getExitEdges(SmallVectorImpl<EdgeT> &ExitEdges) const {
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
- array_pod_sort(LoopBBs.begin(), LoopBBs.end());
-
- typedef GraphTraits<BlockT*> BlockTraits;
- for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
- for (typename BlockTraits::ChildIteratorType I =
- BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
- I != E; ++I)
- if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
- // Not in current loop? It must be an exit block.
- ExitEdges.push_back(EdgeT(*BI, *I));
- }
+ typedef std::pair<const BlockT*, const BlockT*> Edge;
+
+ /// Return all pairs of (_inside_block_,_outside_block_).
+ void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
- /// getLoopPreheader - If there is a preheader for this loop, return it. A
- /// loop has a preheader if there is only one edge to the header of the loop
- /// from outside of the loop. If this is the case, the block branching to the
- /// header of the loop is the preheader node.
+ /// If there is a preheader for this loop, return it. A loop has a preheader
+ /// if there is only one edge to the header of the loop from outside of the
+ /// loop. If this is the case, the block branching to the header of the loop
+ /// is the preheader node.
///
/// This method returns null if there is no preheader for the loop.
- ///
- BlockT *getLoopPreheader() const {
- // Keep track of nodes outside the loop branching to the header...
- BlockT *Out = getLoopPredecessor();
- if (!Out) return 0;
-
- // Make sure there is only one exit out of the preheader.
- typedef GraphTraits<BlockT*> BlockTraits;
- typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out);
- ++SI;
- if (SI != BlockTraits::child_end(Out))
- return 0; // Multiple exits from the block, must not be a preheader.
-
- // The predecessor has exactly one successor, so it is a preheader.
- return Out;
- }
+ BlockT *getLoopPreheader() const;
- /// getLoopPredecessor - If the given loop's header has exactly one unique
- /// predecessor outside the loop, return it. Otherwise return null.
- /// This is less strict that the loop "preheader" concept, which requires
+ /// If the given loop's header has exactly one unique predecessor outside the
+ /// loop, return it. Otherwise return null.
+ /// This is less strict that the loop "preheader" concept, which requires
/// the predecessor to have exactly one successor.
- ///
- BlockT *getLoopPredecessor() const {
- // Keep track of nodes outside the loop branching to the header...
- BlockT *Out = 0;
+ BlockT *getLoopPredecessor() const;
- // Loop over the predecessors of the header node...
- BlockT *Header = getHeader();
- typedef GraphTraits<BlockT*> BlockTraits;
- typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
- for (typename InvBlockTraits::ChildIteratorType PI =
- InvBlockTraits::child_begin(Header),
- PE = InvBlockTraits::child_end(Header); PI != PE; ++PI) {
- typename InvBlockTraits::NodeType *N = *PI;
- if (!contains(N)) { // If the block is not in the loop...
- if (Out && Out != N)
- return 0; // Multiple predecessors outside the loop
- Out = N;
- }
- }
-
- // Make sure there is only one exit out of the preheader.
- assert(Out && "Header of loop has no predecessors from outside loop?");
- return Out;
- }
-
- /// getLoopLatch - If there is a single latch block for this loop, return it.
+ /// If there is a single latch block for this loop, return it.
/// A latch block is a block that contains a branch back to the header.
- BlockT *getLoopLatch() const {
- BlockT *Header = getHeader();
- typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
- typename InvBlockTraits::ChildIteratorType PI =
- InvBlockTraits::child_begin(Header);
- typename InvBlockTraits::ChildIteratorType PE =
- InvBlockTraits::child_end(Header);
- BlockT *Latch = 0;
- for (; PI != PE; ++PI) {
- typename InvBlockTraits::NodeType *N = *PI;
- if (contains(N)) {
- if (Latch) return 0;
- Latch = N;
- }
- }
+ BlockT *getLoopLatch() const;
- return Latch;
+ /// Return all loop latch blocks of this loop. A latch block is a block that
+ /// contains a branch back to the header.
+ void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const {
+ BlockT *H = getHeader();
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+ for (typename InvBlockTraits::ChildIteratorType I =
+ InvBlockTraits::child_begin(H),
+ E = InvBlockTraits::child_end(H); I != E; ++I)
+ if (contains(*I))
+ LoopLatches.push_back(*I);
}
//===--------------------------------------------------------------------===//
// APIs for updating loop information after changing the CFG
//
- /// addBasicBlockToLoop - This method is used by other analyses to update loop
- /// information. NewBB is set to be a new member of the current loop.
+ /// This method is used by other analyses to update loop information.
+ /// NewBB is set to be a new member of the current loop.
/// Because of this, it is added as a member of all parent loops, and is added
/// to the specified LoopInfo object as being in the current basic block. It
/// is not valid to replace the loop header with this method.
- ///
void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
- /// replaceChildLoopWith - This is used when splitting loops up. It replaces
- /// the OldChild entry in our children list with NewChild, and updates the
- /// parent pointer of OldChild to be null and the NewChild to be this loop.
+ /// This is used when splitting loops up. It replaces the OldChild entry in
+ /// our children list with NewChild, and updates the parent pointer of
+ /// OldChild to be null and the NewChild to be this loop.
/// This updates the loop depth of the new child.
- void replaceChildLoopWith(LoopT *OldChild,
- LoopT *NewChild) {
- assert(OldChild->ParentLoop == this && "This loop is already broken!");
- assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
- typename std::vector<LoopT *>::iterator I =
- std::find(SubLoops.begin(), SubLoops.end(), OldChild);
- assert(I != SubLoops.end() && "OldChild not in loop!");
- *I = NewChild;
- OldChild->ParentLoop = 0;
- NewChild->ParentLoop = static_cast<LoopT *>(this);
- }
+ void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
- /// addChildLoop - Add the specified loop to be a child of this loop. This
- /// updates the loop depth of the new child.
- ///
+ /// Add the specified loop to be a child of this loop.
+ /// This updates the loop depth of the new child.
void addChildLoop(LoopT *NewChild) {
- assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
+ assert(!NewChild->ParentLoop && "NewChild already has a parent!");
NewChild->ParentLoop = static_cast<LoopT *>(this);
SubLoops.push_back(NewChild);
}
- /// removeChildLoop - This removes the specified child from being a subloop of
- /// this loop. The loop is not deleted, as it will presumably be inserted
- /// into another loop.
+ /// This removes the specified child from being a subloop of this loop. The
+ /// loop is not deleted, as it will presumably be inserted into another loop.
LoopT *removeChildLoop(iterator I) {
assert(I != SubLoops.end() && "Cannot remove end iterator!");
LoopT *Child = *I;
assert(Child->ParentLoop == this && "Child is not a child of this loop!");
SubLoops.erase(SubLoops.begin()+(I-begin()));
- Child->ParentLoop = 0;
+ Child->ParentLoop = nullptr;
return Child;
}
- /// addBlockEntry - This adds a basic block directly to the basic block list.
+ /// This adds a basic block directly to the basic block list.
/// This should only be used by transformations that create new loops. Other
/// transformations should use addBasicBlockToLoop.
void addBlockEntry(BlockT *BB) {
Blocks.push_back(BB);
+ DenseBlockSet.insert(BB);
}
- /// moveToHeader - This method is used to move BB (which must be part of this
- /// loop) to be the loop header of the loop (the block that dominates all
- /// others).
+ /// interface to reverse Blocks[from, end of loop] in this loop
+ void reverseBlock(unsigned from) {
+ std::reverse(Blocks.begin() + from, Blocks.end());
+ }
+
+ /// interface to do reserve() for Blocks
+ void reserveBlocks(unsigned size) {
+ Blocks.reserve(size);
+ }
+
+ /// This method is used to move BB (which must be part of this loop) to be the
+ /// loop header of the loop (the block that dominates all others).
void moveToHeader(BlockT *BB) {
if (Blocks[0] == BB) return;
for (unsigned i = 0; ; ++i) {
}
}
- /// removeBlockFromLoop - This removes the specified basic block from the
- /// current loop, updating the Blocks as appropriate. This does not update
- /// the mapping in the LoopInfo class.
+ /// This removes the specified basic block from the current loop, updating the
+ /// Blocks as appropriate. This does not update the mapping in the LoopInfo
+ /// class.
void removeBlockFromLoop(BlockT *BB) {
- RemoveFromVector(Blocks, BB);
- }
+ auto I = std::find(Blocks.begin(), Blocks.end(), BB);
+ assert(I != Blocks.end() && "N is not in this list!");
+ Blocks.erase(I);
- /// verifyLoop - Verify loop structure
- void verifyLoop() const {
-#ifndef NDEBUG
- assert(!Blocks.empty() && "Loop header is missing");
-
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
- std::sort(LoopBBs.begin(), LoopBBs.end());
-
- // Check the individual blocks.
- for (block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
- BlockT *BB = *I;
- bool HasInsideLoopSuccs = false;
- bool HasInsideLoopPreds = false;
- SmallVector<BlockT *, 2> OutsideLoopPreds;
-
- typedef GraphTraits<BlockT*> BlockTraits;
- for (typename BlockTraits::ChildIteratorType SI =
- BlockTraits::child_begin(BB), SE = BlockTraits::child_end(BB);
- SI != SE; ++SI)
- if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *SI)) {
- HasInsideLoopSuccs = true;
- break;
- }
- typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
- for (typename InvBlockTraits::ChildIteratorType PI =
- InvBlockTraits::child_begin(BB), PE = InvBlockTraits::child_end(BB);
- PI != PE; ++PI) {
- typename InvBlockTraits::NodeType *N = *PI;
- if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), N))
- HasInsideLoopPreds = true;
- else
- OutsideLoopPreds.push_back(N);
- }
-
- if (BB == getHeader()) {
- assert(!OutsideLoopPreds.empty() && "Loop is unreachable!");
- } else if (!OutsideLoopPreds.empty()) {
- // A non-header loop shouldn't be reachable from outside the loop,
- // though it is permitted if the predecessor is not itself actually
- // reachable.
- BlockT *EntryBB = BB->getParent()->begin();
- for (df_iterator<BlockT *> NI = df_begin(EntryBB),
- NE = df_end(EntryBB); NI != NE; ++NI)
- for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i)
- assert(*NI != OutsideLoopPreds[i] &&
- "Loop has multiple entry points!");
- }
- assert(HasInsideLoopPreds && "Loop block has no in-loop predecessors!");
- assert(HasInsideLoopSuccs && "Loop block has no in-loop successors!");
- assert(BB != getHeader()->getParent()->begin() &&
- "Loop contains function entry block!");
- }
-
- // Check the subloops.
- for (iterator I = begin(), E = end(); I != E; ++I)
- // Each block in each subloop should be contained within this loop.
- for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end();
- BI != BE; ++BI) {
- assert(std::binary_search(LoopBBs.begin(), LoopBBs.end(), *BI) &&
- "Loop does not contain all the blocks of a subloop!");
- }
-
- // Check the parent loop pointer.
- if (ParentLoop) {
- assert(std::find(ParentLoop->begin(), ParentLoop->end(), this) !=
- ParentLoop->end() &&
- "Loop is not a subloop of its parent!");
- }
-#endif
+ DenseBlockSet.erase(BB);
}
- /// verifyLoop - Verify loop structure of this loop and all nested loops.
- void verifyLoopNest() const {
- // Verify this loop.
- verifyLoop();
- // Verify the subloops.
- for (iterator I = begin(), E = end(); I != E; ++I)
- (*I)->verifyLoopNest();
- }
+ /// Verify loop structure
+ void verifyLoop() const;
- void print(raw_ostream &OS, unsigned Depth = 0) const {
- OS.indent(Depth*2) << "Loop at depth " << getLoopDepth()
- << " containing: ";
-
- for (unsigned i = 0; i < getBlocks().size(); ++i) {
- if (i) OS << ",";
- BlockT *BB = getBlocks()[i];
- WriteAsOperand(OS, BB, false);
- if (BB == getHeader()) OS << "<header>";
- if (BB == getLoopLatch()) OS << "<latch>";
- if (isLoopExiting(BB)) OS << "<exiting>";
- }
- OS << "\n";
+ /// Verify loop structure of this loop and all nested loops.
+ void verifyLoopNest(DenseSet<const LoopT*> *Loops) const;
- for (iterator I = begin(), E = end(); I != E; ++I)
- (*I)->print(OS, Depth+2);
- }
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
protected:
friend class LoopInfoBase<BlockT, LoopT>;
- explicit LoopBase(BlockT *BB) : ParentLoop(0) {
+ explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) {
Blocks.push_back(BB);
+ DenseBlockSet.insert(BB);
}
};
return OS;
}
+// Implementation in LoopInfoImpl.h
+extern template class LoopBase<BasicBlock, Loop>;
+
class Loop : public LoopBase<BasicBlock, Loop> {
public:
Loop() {}
- /// isLoopInvariant - Return true if the specified value is loop invariant
- ///
- bool isLoopInvariant(Value *V) const;
+ /// Return true if the specified value is loop invariant.
+ bool isLoopInvariant(const Value *V) const;
- /// hasLoopInvariantOperands - Return true if all the operands of the
- /// specified instruction are loop invariant.
- bool hasLoopInvariantOperands(Instruction *I) const;
+ /// Return true if all the operands of the specified instruction are loop
+ /// invariant.
+ bool hasLoopInvariantOperands(const Instruction *I) const;
- /// makeLoopInvariant - If the given value is an instruction inside of the
- /// loop and it can be hoisted, do so to make it trivially loop-invariant.
+ /// If the given value is an instruction inside of the loop and it can be
+ /// hoisted, do so to make it trivially loop-invariant.
/// Return true if the value after any hoisting is loop invariant. This
/// function can be used as a slightly more aggressive replacement for
/// isLoopInvariant.
///
/// If InsertPt is specified, it is the point to hoist instructions to.
/// If null, the terminator of the loop preheader is used.
- ///
bool makeLoopInvariant(Value *V, bool &Changed,
- Instruction *InsertPt = 0) const;
+ Instruction *InsertPt = nullptr) const;
- /// makeLoopInvariant - If the given instruction is inside of the
- /// loop and it can be hoisted, do so to make it trivially loop-invariant.
+ /// If the given instruction is inside of the loop and it can be hoisted, do
+ /// so to make it trivially loop-invariant.
/// Return true if the instruction after any hoisting is loop invariant. This
/// function can be used as a slightly more aggressive replacement for
/// isLoopInvariant.
/// If null, the terminator of the loop preheader is used.
///
bool makeLoopInvariant(Instruction *I, bool &Changed,
- Instruction *InsertPt = 0) const;
+ Instruction *InsertPt = nullptr) const;
- /// getCanonicalInductionVariable - Check to see if the loop has a canonical
- /// induction variable: an integer recurrence that starts at 0 and increments
- /// by one each time through the loop. If so, return the phi node that
- /// corresponds to it.
+ /// Check to see if the loop has a canonical induction variable: an integer
+ /// recurrence that starts at 0 and increments by one each time through the
+ /// loop. If so, return the phi node that corresponds to it.
///
/// The IndVarSimplify pass transforms loops to have a canonical induction
/// variable.
///
PHINode *getCanonicalInductionVariable() const;
- /// getTripCount - Return a loop-invariant LLVM value indicating the number of
- /// times the loop will be executed. Note that this means that the backedge
- /// of the loop executes N-1 times. If the trip-count cannot be determined,
- /// this returns null.
- ///
- /// The IndVarSimplify pass transforms loops to have a form that this
- /// function easily understands.
- ///
- Value *getTripCount() const;
-
- /// getSmallConstantTripCount - Returns the trip count of this loop as a
- /// normal unsigned value, if possible. Returns 0 if the trip count is unknown
- /// of not constant. Will also return 0 if the trip count is very large
- /// (>= 2^32)
- ///
- /// The IndVarSimplify pass transforms loops to have a form that this
- /// function easily understands.
- ///
- unsigned getSmallConstantTripCount() const;
-
- /// getSmallConstantTripMultiple - Returns the largest constant divisor of the
- /// trip count of this loop as a normal unsigned value, if possible. This
- /// means that the actual trip count is always a multiple of the returned
- /// value (don't forget the trip count could very well be zero as well!).
- ///
- /// Returns 1 if the trip count is unknown or not guaranteed to be the
- /// multiple of a constant (which is also the case if the trip count is simply
- /// constant, use getSmallConstantTripCount for that case), Will also return 1
- /// if the trip count is very large (>= 2^32).
- unsigned getSmallConstantTripMultiple() const;
-
- /// isLCSSAForm - Return true if the Loop is in LCSSA form
+ /// Return true if the Loop is in LCSSA form.
bool isLCSSAForm(DominatorTree &DT) const;
- /// isLoopSimplifyForm - Return true if the Loop is in the form that
- /// the LoopSimplify form transforms loops to, which is sometimes called
- /// normal form.
+ /// Return true if this Loop and all inner subloops are in LCSSA form.
+ bool isRecursivelyLCSSAForm(DominatorTree &DT) const;
+
+ /// Return true if the Loop is in the form that the LoopSimplify form
+ /// transforms loops to, which is sometimes called normal form.
bool isLoopSimplifyForm() const;
- /// hasDedicatedExits - Return true if no exit block for the loop
- /// has a predecessor that is outside the loop.
+ /// Return true if the loop body is safe to clone in practice.
+ bool isSafeToClone() const;
+
+ /// Returns true if the loop is annotated parallel.
+ ///
+ /// A parallel loop can be assumed to not contain any dependencies between
+ /// iterations by the compiler. That is, any loop-carried dependency checking
+ /// can be skipped completely when parallelizing the loop on the target
+ /// machine. Thus, if the parallel loop information originates from the
+ /// programmer, e.g. via the OpenMP parallel for pragma, it is the
+ /// programmer's responsibility to ensure there are no loop-carried
+ /// dependencies. The final execution order of the instructions across
+ /// iterations is not guaranteed, thus, the end result might or might not
+ /// implement actual concurrent execution of instructions across multiple
+ /// iterations.
+ bool isAnnotatedParallel() const;
+
+ /// Return the llvm.loop loop id metadata node for this loop if it is present.
+ ///
+ /// If this loop contains the same llvm.loop metadata on each branch to the
+ /// header then the node is returned. If any latch instruction does not
+ /// contain llvm.loop or or if multiple latches contain different nodes then
+ /// 0 is returned.
+ MDNode *getLoopID() const;
+ /// Set the llvm.loop loop id metadata for this loop.
+ ///
+ /// The LoopID metadata node will be added to each terminator instruction in
+ /// the loop that branches to the loop header.
+ ///
+ /// The LoopID metadata node should have one or more operands and the first
+ /// operand should should be the node itself.
+ void setLoopID(MDNode *LoopID) const;
+
+ /// Return true if no exit block for the loop has a predecessor that is
+ /// outside the loop.
bool hasDedicatedExits() const;
- /// getUniqueExitBlocks - Return all unique successor blocks of this loop.
+ /// Return all unique successor blocks of this loop.
/// These are the blocks _outside of the current loop_ which are branched to.
/// This assumes that loop exits are in canonical form.
- ///
void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
- /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
- /// block, return that block. Otherwise return null.
+ /// If getUniqueExitBlocks would return exactly one block, return that block.
+ /// Otherwise return null.
BasicBlock *getUniqueExitBlock() const;
void dump() const;
+ /// Return the debug location of the start of this loop.
+ /// This looks for a BB terminating instruction with a known debug
+ /// location by looking at the preheader and header blocks. If it
+ /// cannot find a terminating instruction with location information,
+ /// it returns an unknown location.
+ DebugLoc getStartLoc() const {
+ BasicBlock *HeadBB;
+
+ // Try the pre-header first.
+ if ((HeadBB = getLoopPreheader()) != nullptr)
+ if (DebugLoc DL = HeadBB->getTerminator()->getDebugLoc())
+ return DL;
+
+ // If we have no pre-header or there are no instructions with debug
+ // info in it, try the header.
+ HeadBB = getHeader();
+ if (HeadBB)
+ return HeadBB->getTerminator()->getDebugLoc();
+
+ return DebugLoc();
+ }
+
private:
friend class LoopInfoBase<BasicBlock, Loop>;
explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
};
//===----------------------------------------------------------------------===//
-/// LoopInfo - This class builds and contains all of the top level loop
+/// This class builds and contains all of the top-level loop
/// structures in the specified function.
///
template<class BlockT, class LoopT>
class LoopInfoBase {
// BBMap - Mapping of basic blocks to the inner most loop they occur in
- DenseMap<BlockT *, LoopT *> BBMap;
+ DenseMap<const BlockT *, LoopT *> BBMap;
std::vector<LoopT *> TopLevelLoops;
+ std::vector<LoopT *> RemovedLoops;
+
friend class LoopBase<BlockT, LoopT>;
+ friend class LoopInfo;
- void operator=(const LoopInfoBase &); // do not implement
- LoopInfoBase(const LoopInfo &); // do not implement
+ void operator=(const LoopInfoBase &) = delete;
+ LoopInfoBase(const LoopInfoBase &) = delete;
public:
LoopInfoBase() { }
~LoopInfoBase() { releaseMemory(); }
+ LoopInfoBase(LoopInfoBase &&Arg)
+ : BBMap(std::move(Arg.BBMap)),
+ TopLevelLoops(std::move(Arg.TopLevelLoops)) {
+ // We have to clear the arguments top level loops as we've taken ownership.
+ Arg.TopLevelLoops.clear();
+ }
+ LoopInfoBase &operator=(LoopInfoBase &&RHS) {
+ BBMap = std::move(RHS.BBMap);
+
+ for (auto *L : TopLevelLoops)
+ delete L;
+ TopLevelLoops = std::move(RHS.TopLevelLoops);
+ RHS.TopLevelLoops.clear();
+ return *this;
+ }
+
void releaseMemory() {
- for (typename std::vector<LoopT *>::iterator I =
- TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I)
- delete *I; // Delete all of the loops...
+ BBMap.clear();
- BBMap.clear(); // Reset internal state of analysis
+ for (auto *L : TopLevelLoops)
+ delete L;
TopLevelLoops.clear();
+ for (auto *L : RemovedLoops)
+ delete L;
+ RemovedLoops.clear();
}
/// iterator/begin/end - The interface to the top-level loops in the current
/// function.
///
typedef typename std::vector<LoopT *>::const_iterator iterator;
+ typedef typename std::vector<LoopT *>::const_reverse_iterator
+ reverse_iterator;
iterator begin() const { return TopLevelLoops.begin(); }
iterator end() const { return TopLevelLoops.end(); }
+ reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
+ reverse_iterator rend() const { return TopLevelLoops.rend(); }
bool empty() const { return TopLevelLoops.empty(); }
- /// getLoopFor - Return the inner most loop that BB lives in. If a basic
- /// block is in no loop (for example the entry node), null is returned.
- ///
- LoopT *getLoopFor(const BlockT *BB) const {
- typename DenseMap<BlockT *, LoopT *>::const_iterator I=
- BBMap.find(const_cast<BlockT*>(BB));
- return I != BBMap.end() ? I->second : 0;
- }
+ /// Return the inner most loop that BB lives in. If a basic block is in no
+ /// loop (for example the entry node), null is returned.
+ LoopT *getLoopFor(const BlockT *BB) const { return BBMap.lookup(BB); }
- /// operator[] - same as getLoopFor...
- ///
+ /// Same as getLoopFor.
const LoopT *operator[](const BlockT *BB) const {
return getLoopFor(BB);
}
- /// getLoopDepth - Return the loop nesting level of the specified block. A
- /// depth of 0 means the block is not inside any loop.
- ///
+ /// Return the loop nesting level of the specified block. A depth of 0 means
+ /// the block is not inside any loop.
unsigned getLoopDepth(const BlockT *BB) const {
const LoopT *L = getLoopFor(BB);
return L ? L->getLoopDepth() : 0;
}
- // isLoopHeader - True if the block is a loop header node
- bool isLoopHeader(BlockT *BB) const {
+ // True if the block is a loop header node
+ bool isLoopHeader(const BlockT *BB) const {
const LoopT *L = getLoopFor(BB);
return L && L->getHeader() == BB;
}
- /// removeLoop - This removes the specified top-level loop from this loop info
- /// object. The loop is not deleted, as it will presumably be inserted into
+ /// This removes the specified top-level loop from this loop info object.
+ /// The loop is not deleted, as it will presumably be inserted into
/// another loop.
LoopT *removeLoop(iterator I) {
assert(I != end() && "Cannot remove end iterator!");
LoopT *L = *I;
- assert(L->getParentLoop() == 0 && "Not a top-level loop!");
+ assert(!L->getParentLoop() && "Not a top-level loop!");
TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
return L;
}
- /// changeLoopFor - Change the top-level loop that contains BB to the
- /// specified loop. This should be used by transformations that restructure
- /// the loop hierarchy tree.
+ /// Change the top-level loop that contains BB to the specified loop.
+ /// This should be used by transformations that restructure the loop hierarchy
+ /// tree.
void changeLoopFor(BlockT *BB, LoopT *L) {
- LoopT *&OldLoop = BBMap[BB];
- assert(OldLoop && "Block not in a loop yet!");
- OldLoop = L;
+ if (!L) {
+ BBMap.erase(BB);
+ return;
+ }
+ BBMap[BB] = L;
}
- /// changeTopLevelLoop - Replace the specified loop in the top-level loops
- /// list with the indicated loop.
+ /// Replace the specified loop in the top-level loops list with the indicated
+ /// loop.
void changeTopLevelLoop(LoopT *OldLoop,
LoopT *NewLoop) {
- typename std::vector<LoopT *>::iterator I =
- std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop);
+ auto I = std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop);
assert(I != TopLevelLoops.end() && "Old loop not at top level!");
*I = NewLoop;
- assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 &&
+ assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop &&
"Loops already embedded into a subloop!");
}
- /// addTopLevelLoop - This adds the specified loop to the collection of
- /// top-level loops.
+ /// This adds the specified loop to the collection of top-level loops.
void addTopLevelLoop(LoopT *New) {
- assert(New->getParentLoop() == 0 && "Loop already in subloop!");
+ assert(!New->getParentLoop() && "Loop already in subloop!");
TopLevelLoops.push_back(New);
}
- /// removeBlock - This method completely removes BB from all data structures,
+ /// This method completely removes BB from all data structures,
/// including all of the Loop objects it is nested in and our mapping from
/// BasicBlocks to loops.
void removeBlock(BlockT *BB) {
- typename DenseMap<BlockT *, LoopT *>::iterator I = BBMap.find(BB);
+ auto I = BBMap.find(BB);
if (I != BBMap.end()) {
for (LoopT *L = I->second; L; L = L->getParentLoop())
L->removeBlockFromLoop(BB);
static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
const LoopT *ParentLoop) {
- if (SubLoop == 0) return true;
+ if (!SubLoop) return true;
if (SubLoop == ParentLoop) return false;
return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
}
- void Calculate(DominatorTreeBase<BlockT> &DT) {
- BlockT *RootNode = DT.getRootNode()->getBlock();
-
- for (df_iterator<BlockT*> NI = df_begin(RootNode),
- NE = df_end(RootNode); NI != NE; ++NI)
- if (LoopT *L = ConsiderForLoop(*NI, DT))
- TopLevelLoops.push_back(L);
- }
-
- LoopT *ConsiderForLoop(BlockT *BB, DominatorTreeBase<BlockT> &DT) {
- if (BBMap.find(BB) != BBMap.end()) return 0;// Haven't processed this node?
-
- std::vector<BlockT *> TodoStack;
-
- // Scan the predecessors of BB, checking to see if BB dominates any of
- // them. This identifies backedges which target this node...
- typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
- for (typename InvBlockTraits::ChildIteratorType I =
- InvBlockTraits::child_begin(BB), E = InvBlockTraits::child_end(BB);
- I != E; ++I) {
- typename InvBlockTraits::NodeType *N = *I;
- if (DT.dominates(BB, N)) // If BB dominates its predecessor...
- TodoStack.push_back(N);
- }
-
- if (TodoStack.empty()) return 0; // No backedges to this block...
-
- // Create a new loop to represent this basic block...
- LoopT *L = new LoopT(BB);
- BBMap[BB] = L;
-
- BlockT *EntryBlock = BB->getParent()->begin();
-
- while (!TodoStack.empty()) { // Process all the nodes in the loop
- BlockT *X = TodoStack.back();
- TodoStack.pop_back();
-
- if (!L->contains(X) && // As of yet unprocessed??
- DT.dominates(EntryBlock, X)) { // X is reachable from entry block?
- // Check to see if this block already belongs to a loop. If this occurs
- // then we have a case where a loop that is supposed to be a child of
- // the current loop was processed before the current loop. When this
- // occurs, this child loop gets added to a part of the current loop,
- // making it a sibling to the current loop. We have to reparent this
- // loop.
- if (LoopT *SubLoop =
- const_cast<LoopT *>(getLoopFor(X)))
- if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)){
- // Remove the subloop from its current parent...
- assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L);
- LoopT *SLP = SubLoop->ParentLoop; // SubLoopParent
- typename std::vector<LoopT *>::iterator I =
- std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop);
- assert(I != SLP->SubLoops.end() &&"SubLoop not a child of parent?");
- SLP->SubLoops.erase(I); // Remove from parent...
-
- // Add the subloop to THIS loop...
- SubLoop->ParentLoop = L;
- L->SubLoops.push_back(SubLoop);
- }
-
- // Normal case, add the block to our loop...
- L->Blocks.push_back(X);
-
- typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
-
- // Add all of the predecessors of X to the end of the work stack...
- TodoStack.insert(TodoStack.end(), InvBlockTraits::child_begin(X),
- InvBlockTraits::child_end(X));
- }
- }
-
- // If there are any loops nested within this loop, create them now!
- for (typename std::vector<BlockT*>::iterator I = L->Blocks.begin(),
- E = L->Blocks.end(); I != E; ++I)
- if (LoopT *NewLoop = ConsiderForLoop(*I, DT)) {
- L->SubLoops.push_back(NewLoop);
- NewLoop->ParentLoop = L;
- }
-
- // Add the basic blocks that comprise this loop to the BBMap so that this
- // loop can be found for them.
- //
- for (typename std::vector<BlockT*>::iterator I = L->Blocks.begin(),
- E = L->Blocks.end(); I != E; ++I)
- BBMap.insert(std::make_pair(*I, L));
-
- // Now that we have a list of all of the child loops of this loop, check to
- // see if any of them should actually be nested inside of each other. We
- // can accidentally pull loops our of their parents, so we must make sure to
- // organize the loop nests correctly now.
- {
- std::map<BlockT *, LoopT *> ContainingLoops;
- for (unsigned i = 0; i != L->SubLoops.size(); ++i) {
- LoopT *Child = L->SubLoops[i];
- assert(Child->getParentLoop() == L && "Not proper child loop?");
-
- if (LoopT *ContainingLoop = ContainingLoops[Child->getHeader()]) {
- // If there is already a loop which contains this loop, move this loop
- // into the containing loop.
- MoveSiblingLoopInto(Child, ContainingLoop);
- --i; // The loop got removed from the SubLoops list.
- } else {
- // This is currently considered to be a top-level loop. Check to see
- // if any of the contained blocks are loop headers for subloops we
- // have already processed.
- for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) {
- LoopT *&BlockLoop = ContainingLoops[Child->Blocks[b]];
- if (BlockLoop == 0) { // Child block not processed yet...
- BlockLoop = Child;
- } else if (BlockLoop != Child) {
- LoopT *SubLoop = BlockLoop;
- // Reparent all of the blocks which used to belong to BlockLoops
- for (unsigned j = 0, f = SubLoop->Blocks.size(); j != f; ++j)
- ContainingLoops[SubLoop->Blocks[j]] = Child;
-
- // There is already a loop which contains this block, that means
- // that we should reparent the loop which the block is currently
- // considered to belong to to be a child of this loop.
- MoveSiblingLoopInto(SubLoop, Child);
- --i; // We just shrunk the SubLoops list.
- }
- }
- }
- }
- }
-
- return L;
- }
-
- /// MoveSiblingLoopInto - This method moves the NewChild loop to live inside
- /// of the NewParent Loop, instead of being a sibling of it.
- void MoveSiblingLoopInto(LoopT *NewChild,
- LoopT *NewParent) {
- LoopT *OldParent = NewChild->getParentLoop();
- assert(OldParent && OldParent == NewParent->getParentLoop() &&
- NewChild != NewParent && "Not sibling loops!");
-
- // Remove NewChild from being a child of OldParent
- typename std::vector<LoopT *>::iterator I =
- std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(),
- NewChild);
- assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??");
- OldParent->SubLoops.erase(I); // Remove from parent's subloops list
- NewChild->ParentLoop = 0;
-
- InsertLoopInto(NewChild, NewParent);
- }
-
- /// InsertLoopInto - This inserts loop L into the specified parent loop. If
- /// the parent loop contains a loop which should contain L, the loop gets
- /// inserted into L instead.
- void InsertLoopInto(LoopT *L, LoopT *Parent) {
- BlockT *LHeader = L->getHeader();
- assert(Parent->contains(LHeader) &&
- "This loop should not be inserted here!");
-
- // Check to see if it belongs in a child loop...
- for (unsigned i = 0, e = static_cast<unsigned>(Parent->SubLoops.size());
- i != e; ++i)
- if (Parent->SubLoops[i]->contains(LHeader)) {
- InsertLoopInto(L, Parent->SubLoops[i]);
- return;
- }
-
- // If not, insert it here!
- Parent->SubLoops.push_back(L);
- L->ParentLoop = Parent;
- }
+ /// Create the loop forest using a stable algorithm.
+ void analyze(const DominatorTreeBase<BlockT> &DomTree);
// Debugging
+ void print(raw_ostream &OS) const;
- void print(raw_ostream &OS) const {
- for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
- TopLevelLoops[i]->print(OS);
- #if 0
- for (DenseMap<BasicBlock*, LoopT*>::const_iterator I = BBMap.begin(),
- E = BBMap.end(); I != E; ++I)
- OS << "BB '" << I->first->getName() << "' level = "
- << I->second->getLoopDepth() << "\n";
- #endif
- }
+ void verify() const;
};
-class LoopInfo : public FunctionPass {
- LoopInfoBase<BasicBlock, Loop> LI;
- friend class LoopBase<BasicBlock, Loop>;
-
- void operator=(const LoopInfo &); // do not implement
- LoopInfo(const LoopInfo &); // do not implement
-public:
- static char ID; // Pass identification, replacement for typeid
-
- LoopInfo() : FunctionPass(ID) {
- initializeLoopInfoPass(*PassRegistry::getPassRegistry());
- }
-
- LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; }
-
- /// iterator/begin/end - The interface to the top-level loops in the current
- /// function.
- ///
- typedef LoopInfoBase<BasicBlock, Loop>::iterator iterator;
- inline iterator begin() const { return LI.begin(); }
- inline iterator end() const { return LI.end(); }
- bool empty() const { return LI.empty(); }
-
- /// getLoopFor - Return the inner most loop that BB lives in. If a basic
- /// block is in no loop (for example the entry node), null is returned.
- ///
- inline Loop *getLoopFor(const BasicBlock *BB) const {
- return LI.getLoopFor(BB);
- }
-
- /// operator[] - same as getLoopFor...
- ///
- inline const Loop *operator[](const BasicBlock *BB) const {
- return LI.getLoopFor(BB);
- }
-
- /// getLoopDepth - Return the loop nesting level of the specified block. A
- /// depth of 0 means the block is not inside any loop.
- ///
- inline unsigned getLoopDepth(const BasicBlock *BB) const {
- return LI.getLoopDepth(BB);
- }
-
- // isLoopHeader - True if the block is a loop header node
- inline bool isLoopHeader(BasicBlock *BB) const {
- return LI.isLoopHeader(BB);
- }
-
- /// runOnFunction - Calculate the natural loop information.
- ///
- virtual bool runOnFunction(Function &F);
-
- virtual void verifyAnalysis() const;
+// Implementation in LoopInfoImpl.h
+extern template class LoopInfoBase<BasicBlock, Loop>;
- virtual void releaseMemory() { LI.releaseMemory(); }
+class LoopInfo : public LoopInfoBase<BasicBlock, Loop> {
+ typedef LoopInfoBase<BasicBlock, Loop> BaseT;
- virtual void print(raw_ostream &O, const Module* M = 0) const;
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
-
- /// removeLoop - This removes the specified top-level loop from this loop info
- /// object. The loop is not deleted, as it will presumably be inserted into
- /// another loop.
- inline Loop *removeLoop(iterator I) { return LI.removeLoop(I); }
+ friend class LoopBase<BasicBlock, Loop>;
- /// changeLoopFor - Change the top-level loop that contains BB to the
- /// specified loop. This should be used by transformations that restructure
- /// the loop hierarchy tree.
- inline void changeLoopFor(BasicBlock *BB, Loop *L) {
- LI.changeLoopFor(BB, L);
- }
+ void operator=(const LoopInfo &) = delete;
+ LoopInfo(const LoopInfo &) = delete;
+public:
+ LoopInfo() {}
+ explicit LoopInfo(const DominatorTreeBase<BasicBlock> &DomTree);
- /// changeTopLevelLoop - Replace the specified loop in the top-level loops
- /// list with the indicated loop.
- inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
- LI.changeTopLevelLoop(OldLoop, NewLoop);
+ LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast<BaseT &>(Arg))) {}
+ LoopInfo &operator=(LoopInfo &&RHS) {
+ BaseT::operator=(std::move(static_cast<BaseT &>(RHS)));
+ return *this;
}
- /// addTopLevelLoop - This adds the specified loop to the collection of
- /// top-level loops.
- inline void addTopLevelLoop(Loop *New) {
- LI.addTopLevelLoop(New);
- }
+ // Most of the public interface is provided via LoopInfoBase.
- /// removeBlock - This method completely removes BB from all data structures,
- /// including all of the Loop objects it is nested in and our mapping from
- /// BasicBlocks to loops.
- void removeBlock(BasicBlock *BB) {
- LI.removeBlock(BB);
- }
+ /// Update LoopInfo after removing the last backedge from a loop. This updates
+ /// the loop forest and parent loops for each block so that \c L is no longer
+ /// referenced, but does not actually delete \c L immediately. The pointer
+ /// will remain valid until this LoopInfo's memory is released.
+ void markAsRemoved(Loop *L);
- /// replacementPreservesLCSSAForm - Returns true if replacing From with To
- /// everywhere is guaranteed to preserve LCSSA form.
+ /// Returns true if replacing From with To everywhere is guaranteed to
+ /// preserve LCSSA form.
bool replacementPreservesLCSSAForm(Instruction *From, Value *To) {
// Preserving LCSSA form is only problematic if the replacing value is an
// instruction.
// it as a replacement will not break LCSSA form.
return ToLoop->contains(getLoopFor(From->getParent()));
}
-};
+ /// Checks if moving a specific instruction can break LCSSA in any loop.
+ ///
+ /// Return true if moving \p Inst to before \p NewLoc will break LCSSA,
+ /// assuming that the function containing \p Inst and \p NewLoc is currently
+ /// in LCSSA form.
+ bool movementPreservesLCSSAForm(Instruction *Inst, Instruction *NewLoc) {
+ assert(Inst->getFunction() == NewLoc->getFunction() &&
+ "Can't reason about IPO!");
+
+ auto *OldBB = Inst->getParent();
+ auto *NewBB = NewLoc->getParent();
+
+ // Movement within the same loop does not break LCSSA (the equality check is
+ // to avoid doing a hashtable lookup in case of intra-block movement).
+ if (OldBB == NewBB)
+ return true;
+
+ auto *OldLoop = getLoopFor(OldBB);
+ auto *NewLoop = getLoopFor(NewBB);
+
+ if (OldLoop == NewLoop)
+ return true;
+
+ // Check if Outer contains Inner; with the null loop counting as the
+ // "outermost" loop.
+ auto Contains = [](const Loop *Outer, const Loop *Inner) {
+ return !Outer || Outer->contains(Inner);
+ };
+
+ // To check that the movement of Inst to before NewLoc does not break LCSSA,
+ // we need to check two sets of uses for possible LCSSA violations at
+ // NewLoc: the users of NewInst, and the operands of NewInst.
+
+ // If we know we're hoisting Inst out of an inner loop to an outer loop,
+ // then the uses *of* Inst don't need to be checked.
+
+ if (!Contains(NewLoop, OldLoop)) {
+ for (Use &U : Inst->uses()) {
+ auto *UI = cast<Instruction>(U.getUser());
+ auto *UBB = isa<PHINode>(UI) ? cast<PHINode>(UI)->getIncomingBlock(U)
+ : UI->getParent();
+ if (UBB != NewBB && getLoopFor(UBB) != NewLoop)
+ return false;
+ }
+ }
+
+ // If we know we're sinking Inst from an outer loop into an inner loop, then
+ // the *operands* of Inst don't need to be checked.
+
+ if (!Contains(OldLoop, NewLoop)) {
+ // See below on why we can't handle phi nodes here.
+ if (isa<PHINode>(Inst))
+ return false;
+
+ for (Use &U : Inst->operands()) {
+ auto *DefI = dyn_cast<Instruction>(U.get());
+ if (!DefI)
+ return false;
+
+ // This would need adjustment if we allow Inst to be a phi node -- the
+ // new use block won't simply be NewBB.
+
+ auto *DefBlock = DefI->getParent();
+ if (DefBlock != NewBB && getLoopFor(DefBlock) != NewLoop)
+ return false;
+ }
+ }
+
+ return true;
+ }
+};
// Allow clients to walk the list of nested loops...
template <> struct GraphTraits<const Loop*> {
}
};
-template<class BlockT, class LoopT>
-void
-LoopBase<BlockT, LoopT>::addBasicBlockToLoop(BlockT *NewBB,
- LoopInfoBase<BlockT, LoopT> &LIB) {
- assert((Blocks.empty() || LIB[getHeader()] == this) &&
- "Incorrect LI specified for this loop!");
- assert(NewBB && "Cannot add a null basic block to the loop!");
- assert(LIB[NewBB] == 0 && "BasicBlock already in the loop!");
-
- LoopT *L = static_cast<LoopT *>(this);
-
- // Add the loop mapping to the LoopInfo object...
- LIB.BBMap[NewBB] = L;
-
- // Add the basic block to this loop and all parent loops...
- while (L) {
- L->Blocks.push_back(NewBB);
- L = L->getParentLoop();
+/// \brief Analysis pass that exposes the \c LoopInfo for a function.
+class LoopAnalysis {
+ static char PassID;
+
+public:
+ typedef LoopInfo Result;
+
+ /// \brief Opaque, unique identifier for this analysis pass.
+ static void *ID() { return (void *)&PassID; }
+
+ /// \brief Provide a name for the analysis for debugging and logging.
+ static StringRef name() { return "LoopAnalysis"; }
+
+ LoopInfo run(Function &F, AnalysisManager<Function> *AM);
+};
+
+/// \brief Printer pass for the \c LoopAnalysis results.
+class LoopPrinterPass {
+ raw_ostream &OS;
+
+public:
+ explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {}
+ PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
+
+ static StringRef name() { return "LoopPrinterPass"; }
+};
+
+/// \brief The legacy pass manager's analysis pass to compute loop information.
+class LoopInfoWrapperPass : public FunctionPass {
+ LoopInfo LI;
+
+public:
+ static char ID; // Pass identification, replacement for typeid
+
+ LoopInfoWrapperPass() : FunctionPass(ID) {
+ initializeLoopInfoWrapperPassPass(*PassRegistry::getPassRegistry());
}
-}
+
+ LoopInfo &getLoopInfo() { return LI; }
+ const LoopInfo &getLoopInfo() const { return LI; }
+
+ /// \brief Calculate the natural loop information for a given function.
+ bool runOnFunction(Function &F) override;
+
+ void verifyAnalysis() const override;
+
+ void releaseMemory() override { LI.releaseMemory(); }
+
+ void print(raw_ostream &O, const Module *M = nullptr) const override;
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+};
+
+/// \brief Pass for printing a loop's contents as LLVM's text IR assembly.
+class PrintLoopPass {
+ raw_ostream &OS;
+ std::string Banner;
+
+public:
+ PrintLoopPass();
+ PrintLoopPass(raw_ostream &OS, const std::string &Banner = "");
+
+ PreservedAnalyses run(Loop &L);
+ static StringRef name() { return "PrintLoopPass"; }
+};
} // End llvm namespace